Method of printing on paper and resultant article



United States Patent Ofiice 3,029,154 Patented Apr. 10, 1962 3,029,154METHGD F PRINTING 0N PAPER AND RESULTANT ARTICLE Ales Maria Kapral,Kingstord, near Sydney, New South Wales, Australia, assignor to ProcessMethods Corporation, Chicago, Ill., a corporation of Hlinois No Drawing.Filed Mar. 29, 1957, Ser. No. 649,276 Claims priority, applicationAustralia Feb. 1, 1957 30 Claims. (Cl. 117-15) This invention relates tothe art of printing, and it is concerned principally with the printingof newspapers and books, although it is applicable to any other printedmatter. The invention can be used genrally, for all methods of printing,for instance by letterpress, rotary press, lithography, Linotype and inall other methods involving the transfer of printing ink onto a paper,board or similar surface, although in the following descriptionreference will be made to paper only, for the sake of simplicity.

One object of the invention is to provide a method of printing by theuse of which the depth of penetration of the paper by the printing inkis reduced whereby an improved quality of the print and an increaseddrying rate of the printing ink is achieved.

The reduction in the depth of penetration by the printing ink leads to areduced consumption of ink and therefore to an increased economy of theprinting process.

A further effect achieved according to the invention by the reduction inthe depth of ink penetration is that the thickness of the paper requiredfor achieving sufficient opacity to enable both sides of the paper to beprinted, is reduced as well which, in turn, can lead to increasedeconomy in the amount of paper pul required for the production, forinstance of newsprint.

During a study of the drying time of different printing inks used inhigh-speed rotary processes, and of the penetration of solventscontained in printing inks into the fibres of paper, it was observedthat a porous surface coated with a thin continuous layer of one or moreof certain metallic salts of higher fatty acids such as for instancestearates, resinates, oleates, linoleates and naphthanates of suchmetals as manganese, zinc, iron, nickel, aluminium, cobalt, chromium,magnesium and copper, have a high affinity for printing ink, providedthese metallic salts are unmixed with or do not contain any excessivequantities of incompatible ingredients such as clay or other fillers,and provided further that the printing ink contains a solvent of themetallic salt or salts forming the layer such as, for instance,vegetable or mineral oils, oxidised oils and hydrocarbons.

It was also found that the solvent content of the ink penetrates intothe paper which, when coated as stated above, is usuallywater-repellent, and dissolves some of the metallic salt coating. As aresult of such dissolution the solvent of the ink is thickened and itsfurther penetration into the paper is impeded, such penetration beingfurther increased owing to the drying effect of the metallic salts inquestion, on the siccative oils used in printing inks. It appears that,owing to the fact that the ink and the salt are brought together on afibrous substrate of very large micro-porous area, the oxidationreaction involved in the drying of the oil takes place more rapidly thanit would if such a salt were mixed into the ink at a similar temperatureprior to printing.

The latter effect is of great value in connection with newspaperprinting where the presses operate at great speed, and the papers aresold very soon after printing. The quick drying achieved by theapplication of the invention assists in preventing smudging of freshprint.

The invention thus consists in a method of printing which includes thesteps of selecting a paper coated on its surface with a thin continuouslayer of one or more than one metallic salt of one or more than onelongchain carboxylic acid having a chain-length of at least elevencarbon atoms in the molecule, the metal having a valency of at leasttwo, and of transferring to the surface of said paper a printing inkwhich includes in its composition a. solvent for said metallic salt orsalts.

Moreover, the invention comprises any article of printed matter printedby the method so defined.

The application of a suitable surface layer of metallic salt to papermay be carried out in a number of ways, for instance by the methoddescribed in my co-pending application Serial No. 583,479, filed May 8,1956, now US. Patent No. 2,982,675, or in my further co-pendingapplication Serial No. 649,381, filed March 29, 1957. The presentinvention is, however, not concerned with a particular method ofapplication, and suitable methods will therefore not be described exceptto state that it may be carried out, for example by the use of anappropriate solvent which is afterwards evaporated or by a double-stepreaction used for forming metallic soaps. It is however, not suflicientto incorporate such metallic salt in the paper pulp, but it must existas a layer on the surface of the paper.

In the following, a number of examples are given for the purpose ofillustrating the invention, and not with a view to limiting the ambit ofthe invention to these particular examples.

Example 1 A. surface coat of zinc stearate was applied to whitelithe-paper having a weight of 136 gins/m the weight of the coat beingof the order of 0.3% calculated on the paper weight. The paper so coatedwas printed with printing ink of normal composition, i.e. containingabout 70% of carbon black and about 30% of rosin oil with a trace ofcobalt acetate, to which 5% of linseed oil was added, all percentagesbeing by Weight, the linseed oil in particular acting as a solvent forzine stearate and thereby assisting in reducing the drying time.

It was observed that the saving of ink achieved when printing on paperso coated was 25% as compared with printing on uncoated paper of thesame specification with the same ink, but was about 27% if ink of normalcomposition was used. It was further observed that the drying time wasreduced to 8 hours with the ink containing linseed oil and to 9 /2 hourswith the ink of normal composition as against the required drying timeof 12 hours for the uncoated paper. The print itself was more sharp andthe color of the print brighter with each type of ink if coated paperwas used.

Example 2 A surface coat of zinc stearate was applied to whitelitho-paper having a weight of 136 gms./rn. the weight of the coat beingof the order of 0.8% calculated on the paper weight. The paper so coatedwas printed with printing ink of the normal composition (see Example 1)to which 5% by weight of linseed oil was added.

It was observed that the saving of ink achieved when printing on thepaper so coated was 30% as compared with printing on uncoated paper ofthe same specification with the ink containing the linseed oil, but was32% if ink of normal composition was used. The drying time was reducedto 6 hours as against 8 hours for the uncoated paper and ink dilutedwith linseed oil, but was reduced to 7 hours only when ink of normalcomposition was used. The print itself was more sharp and the color ofthe print brighter with each type of ink if coated paper was used.

Example 3 Like Example 2 except for the fact that 20% by weight oflinseed oil was added to the normal printing ink. In this case thesaving of ink amounted to 35% as compared with printing on uncoatedpaper of the same specification with the same ink. The drying time wasfound to be 4 /2 hours as against 12 hours in the case of the uncoatedpaper, and the print proved to be very sharp and bright.

' Example 4 A superficial coat of cobalt resinate which is substantiallya cobalt salt of abietic acid, was applied to the surface of so-calledsystem board having a weight of 150 grns./m. the weight of the coatbeing 0.05% calculated on the paper weight. The paper so coated wasprinted in multi-color by a wet process with blue and yellow printinginks each containing about 70% by weight of pigment (Prussian blue andchrome yellow, respectively) and about 30% of rosin oil with a trace ofcobalt acetate, with 5% by weight of kerosene added to each of theseinks, the kerosene acting as a solvent for the cobalt resinate andthereby promoting the drying of the ink.

The saving of blue ink amounted to 20% and that of yellow ink to 35% ascompared with printing with the same inks on uncoated paper of the samequality. The drying time was hours as compared with 24 hours in the caseof uncoated paper. The print proved to be clearer than on uncoatedpaper, and the mixing of colors easier to effect.

Example 5 Like Example 4, except that the cobalt resinate coat wasconsiderably thicker, its weight being 2% calculated on the paperweight.

The saving of blue ink amounted to 50%, and that of yellow ink to 35%,as compared with printing with the same inks on uncoated paper of thesame quality. The drying time however was very considerably reduced to 2hours as against 24 hours in the case of the uncoated paper. The printproved to be sufficiently clear and the different colors could beapplied to the paper in immediate succession, without aftecting thequality of the print.

A comparison of Example 4 with Example 5 shows that with increasingthickness of the cobalt resinate coat, the drying time could be reducedvery considerably. In the actual practice of printing however, suchheavy coats would not be used for reasons of economy. Besides this, theapplication of a thick coat tends to reduce the number of pores in thepaper and consequently affects the penetration of the ink into thelatter. As a result a more satisfactory quality of the print is achievedwith a comparatively thinner coat of cobalt resinate.

Example 6 The same as in Example 5, with the exception of the printingink which contained 5% by weight of paraffin oil and 5% by weight ofkerosene. The saving of ink and the reduction in drying time were thesame as those observed in Example 5.

Example 7 A coat of manganese salt of oleic acid was applied to thesurface of white lithe-paper having a weight of 150 gms/mfl, the weightof the coat being 2.5% calculated on the paper weight. This paper wasprinted with black printing ink of normal composition diluted with 40%by weight of boiled linseed oil, the latter acting as a solvent for themanganese salt.

The saving of ink obtained when printing on the coated paper was about30% as compared with printing on incoated paper of the same quality withthe same ink. The drying time was reduced to 6 hours, from 18 hoursrequired for the untreated paper.

Example 8 A surface coat of equal parts of copper salts of stearic andoleic acids was applied to white litho-paper having a Weight of 136gms./m. the weight of the coat being 2.8% calculated on the paperweight. This paper was printed with black ink of normal compositioncontaining additionally 10% by weight of soya bean oil. The saving ofink achieved by printing on the coated paper as compared with printingwith the same ink on uncoated paper of the same quality was about 50%.The drying time was reduced from 20 hours in the case of the uncoatedpaper, to 8 hours in the case of the coated paper. The print was verysharp and clear, even though the printing block showed considerablewear.

Moreover it was observed that the printing speed could be increased by25% without any ill effect on the quality of the print, presumably dueto the reduced adhesion of the paper to the block during the printingprocess.

Example 9 A surface coat of aluminium stearate was applied to whitelitho-paper weighing 136 gms./m. the weight of the coat being 0.5%calculated on the paper weight. The coated paper was printed with normalblack printing ink containing additionally 10% by weight of kerosenewhich acts as a solvent and therefore as an activator for the aluminiumstearate.

The saving of ink obtained when printing on paper so coated was 39%,compared with printing on uncoated paper of the same specification withthe same ink. The necessary drying time was reduced to 3 hours from 9hours required for the untreated paper. In this case also, the printproved to be more distinct and sharp, and of deeper blackness than inthe case of the untreated paper.

Example 10 Like Example 9, except that the weight of the coat ofaluminium stearate was 3% of that or the paper.

The saving of ink observed in this case was 40% compared with printingon uncoated paper of the same specification with the same ink, whereasthe drying time was reduced from 9 hours to 4 hours only. The quality ofthe print was substantially the same as that achieved in Example 9.

By comparing the results of Examples 9 and 10 it will be seen that theuse of a thicker coat is hardly warranted. The gain, if any, in thesaving of printing ink is negligible, whereas the reduction in dryingtime is less.

Example 11 The same type of paper as in Example 9 had applied to itssurface a coat of aluminium stearate, the weight of the coat being 3% ofthat of the paper itself. The coated paper was printed with normal blackprinting ink containing additionally 5% by weight of boiled linseed oiland 30% by weight of kerosene. The saving of ink by printing on thecoated paper, as compared with printing on the uncoated paper, was about50%, and the drying time was reduced to 3 hours from 10 hours. Hereagain the print proved to be more distinct, sharp, and of deeperblackness than in the case of the untreated paper.

When comparing the results obtained with Example 10 it will be seen thatthe increased quantity of solvent and activator for the aluminiumstearate caused'a comparative reduction in the drying time.

Example 12 To standard newsprint a coat or layer of aluminium stearatewas applied, the coat increasing the paper weight by 0.9%. The paper wasprinted on a standard rotary the same working conditions. immediatelyafter leaving the press, smudging being altogether eliminated. The printproved to be very sharp and of a deep black color.

Example 13 Like Example 12, except that the coat of aluminium stearateincreased the paper weight by 1.6%. The saving of ink was therebyincreased to about 53% under the same working conditions. it wouldappear that the increased saving of ink does not justify the use of athicker coat on either economical or any other grounds.

Example 14 A coat of nickel resinate, being substantially a salt ofabietic acid, was applied to the surface of white lithopaper having aweight of about 136 gms./m. the weight of the coat being 0.05%calculated on the paper weight. The coated paper was printed with normalprinting inks of difierent colors each with an addition of 20% by weightof boiled linseed oil which acts as a solvent and activator for thenickel resinate.

The saving of printing ink on the coated paper was 15 to 20%, ascompared with printing on uncoated paper of the same quality with thesame ink. The drying time was reduced to 6 hours from 12 hours for theuntreated paper. All colors showed increased brightness when comparedwith printing on the untreated paper.

The examples described above illustrate that in printing on a porouspaper surface coated with a continuous layer of one or more than oneWater-insoluble higher fatty acid salt of a metal having a valency of atleast two, great advantages of an unexpected nature are achieved whichinclude a considerable saving of printing ink and a notable reduction ofthe drying time as compared with printing on paper devoid of such coat.A further important advantage lies in the fact that due to the saving ofprinting ink and the considerable reduction of lateral flow of inkacross the paper fibres, the clarity of the print is greatly enhanced.These advantages can be achieved with printing inks of normalcomposition Which always contain rosin oil or some other oil and/orhydrocarbons as oleaginous vehicle for the pigment or pigments, saidoleaginous matter acting as a solvent for said metallic salt and therebycausing the salt to act as an effective drier for the ink, in additionto such drier or driers as are usually contained in printing inks insmall quantities.

For carrying out the method according to the invention anywater-insoluble salt of a metal having a valency of at least two with along-chain carboxylic acid having a chain-length from 11 to 20 carbonatoms can be used, in theory. Many such salts, however, will be excludedin practice, either for reasons of economy or because of the toxicity ofsuch salts. Others, such as iron and magnesium salts, will not normallybe used in practice as these salts are not considered effective driersunless subjected to additional treatment. Copper salts if used in theprocess usually give to the paper a bluish tinge. Therefore they may beused with advantage on off-white paper for the purpose of reducing itsyellowish tint. As a rule, however, they will not be used on paper ofsufiicient whiteness.

Amongst the long-chain carboxylic acids, those of natural origin havinga chain-length from 12 to 20 are preferred, mainly because they arecomparatively inexpensive, but synthetic long-chain carboxylic acidshaving chain-lengths of 11, 13, 15 or 17 carbon atoms are also usablefor the purpose.

The thickness of the coat on the paper may vary within wide limits. Itis preferably determined by comparing the weight of the uncoated paperwith that of the coated paper. If the coat contains salts which arehighly effective as driers. such as cobalt resinates or nickelresinates, it may then be very thin, for instance so thin that the Theprint dried almost weight of commercial types of paper is increased byabout 0.02 to 0.1% only. If other salts such as zinc stearate oraluminium stearate are used, the required increase of the paper weightmay be between 0.2% and 1.6%, depending on the extent of saving in inkand/or of the reduction in the drying time aimed at. In general, verysatisfactory results are achieved with coats of zinc stearate oraluminium stearate which increase the paper weight by between 0.5 to 1%.

The coat or layer of water-insoluble salt will adhere to the papersurface more or less permanently, depending on the method used for theapplication or precipitation of the salt on the paper surface. It isdesirable, however, to assure permanency of the coat by embedding samein a suitable fixative. One method of so embedding the salt or salts isdescribed for instance in my copending patent application Serial No.649,381 of March 29, 1957, entitled Paper, Particularly Printing Paper,and Method of Making Same.

As pointed out above, the advantages of the invention are attained withpractically any type of printing ink containing rosin oil or some otheroil and/or hydrocarbon as oleaginous vehicle. The percentages inprinting ink of pigment or pigments and vehicle substance vary Widely,depending on the particular nature of the pigment or pigments. Thepercentages stated above in Examples 1 and 4 must not therefore be takenas limiting the scope of invention to any particular type of printingink, but as representing only those types of inks which were availableto the applicant for his experiments.

Quantities of linseed oil, kerosene and/or other oils and hydrocarbonsvarying between about 2% and 30 to 40% of the undiluted ink will in mostcases be added only if it desired to obtain a considerable reduction ofthe drying time.

What I claim is:

1. Method of printing on paper, paper-board and the like with printingink containing at least a pigment and an oleaginous vehicle, whichcomprises applying sad printing ink to a paper, paper-board and the likeprovided on the surface to be printed with a thin and continuous coatconsisting essentially of a water-insoluble higher fatty acid salt of ametal having a valency of at. least two, said continuous coat beingpresent upon said paper prior to the application of said printing inkthereto and said coat and said printing ink being difierent from eachother and wholly independent of each other prior to said application,and said oleaginous vehicle having a solvent action upon said salt insaid coat and said salt in said coat having a drying action upon saidink, whereby mutual interaction between said coat and said ink occurs.

2. The method as claimed in claim 1, wherein said water-insoluble saltis a salt of a long-chain carboxylic acid having a chain-length from 11to 20 carbon atoms.

3. The method as claimed in claim 2, wherein the printing ink is dilutedby the addition thereto of one member of the group consisting of linseedoil, boiled linseed oil, kerosene, paraffin oil and soya bean oil.

4. The method as claimed in claim 3, wherein the quantity of the diluentadded to the printing ink is between 2% and 40% by weight.

5. The method as claimed in claim 4, wherein the quantity of the diluentadded to the printing inkis between 5% and 10% by weight.

6. The method as claimed in claim 1, wherein said coat includes at leastone member of the group consisting of zinc stearate, aluminium stearate,copper stearate and copper oleate.

7. The method as claimed in claim 6, wherein the increase of the paperweight by the application of said coat is from about 0.2% to about 1.6%.

8. The method as claimed in claim 6, wherein the increase of the paperweight by the application of said coat is from about 0.5% to about 1%.

9. The method as claimed in claim 6, wherein the 7 printing ink isdiluted by the addition thereto of at least one member of the groupconsisting of linseed oil, boiled linseed oil, kerosene, paraffin oiland soya bean oil.

10. The method as claimed in claim 1, wherein said coat includes atleast one member of the group consisting of cobalt resinate and nickelresinate.

11. The method as claimed in claim 10, wherein the increase of thepaperweight by the application of said coat is from about 0.02% to about0.1%.

12. The method as claimed in claim 10, wherein the printing ink isdiluted by the addition thereto of at least one member of the groupconsisting of linseed oil, boiled linseed oil, kerosene, paraffin oiland soya bean oil.

13. The method as claimed in claim 1, wherein the printing ink isdiluted by the addition thereto of a solvent for the water-insolublehigher fatty acid salt of a metal having a valency of at least two.

14. The method as claimed in claim 1, wherein the printing ink isdiluted by the addition thereto of one member of the group consisting oflinseed oil, boiled linseed oil, kerosene, paraffin oil and soya beanoil.

15. The method as claimed in claim 13, wherein quantity of the diluentadded to the printing ink is tween 2% and 40% by weight.

16. The method as claimed in claim 14, wherein quantity of the diluentadded to the printing ink is tween 2% and 40% by weight.

17. The method as claimed in claim 15, wherein quantity of the diluentadded to the printing ink is tween 5% and by weight.

18. The method as claimed in claim 16, wherein quantity of the diluentadded to the printing ink is tween 5% and 10% by weight.

19. A web of paper, paperboard and the like having on at least one facethereof a thin and continuous coat consisting essentially of awater-insoluble higher fatty acid salt of a metal having a valency of atleast two and the residue of a printing ink overlying and combined withat least a portion of said coat, said ink including a pigment and anoleaginous vehicle, said oleaginous vehicle having a solvent action uponsaid sailt in said coat, and said salt in said coat having a dryingaction upon said ink, whereby said residue comprises the products ofinteraction between said ink and said coat.

20. A web as defined in claim 19, wherein said coat includes at leastone member of the group consisting of zinc stearate, aluminium stearate,copper stearate and copper oleate.

21. A web as defined in claim 19, wherein said coat increases the weightof said web by 0.5 to 1%.

22. A -web as defined in claim 19, wherein said coat the bethe bethebethe beincludes at least one member of the group consisting of cobaltresinate and nickel resinate.

23. A web as defined in claim 22, wherein said coat increases the weightof said web by 0.5 to 1%.

24. A web as defined in claim 22, wherein said ink includes a furthersolvent for said salt.

25. A web as defined in claim 24, wherein the quantity of said solventis between 2% and 40% by weight of said ink.

26. A web as defined in claim 19, wherein the printing ink is diluted bythe addition thereto of one member of the group consisting of linseedoil, boiled linseed oil, kerosene, paraffin oil and soya bean oil.

27. A web as defined in claim 26, wherein the quantity of said diluentis between 2% and 10% by weight of said ink.

28. A web as defined in claim 26, wherein the quantity of said diluentis between 5% and 10% by weight of said ink.

29. A web as defined in claim 19, wherein said coat includes at leastone member of the group consisting of zinc stearate, aluminium stearate,copper stearate and copper oleate and wherein the printing ink isdiluted by the addition thereto of at least one member of the groupconsisting of linseed oil, boiled linseed oil, kerosene, paraffin oiland soya bean oil.

30. A web as defined in claim 19, wherein the quantity of the diluentadded to the printing ink is between 5% and 10% by weight and whereinthe printing ink is diluted by the addition thereto of at least onemember of the group consisting of linseed oil, boiled linseed oil,kerosene, paraffin oil and soya bean oil.

References Cited in the file of this patent UNITED STATE S PATENTS1,430,998 Hoskins Oct. 3, 1922 1,811,804 Poschel June 23, 1931 1,829,877Schroeder Nov. 3, 1931 2,204,550 Murray June 18, 1940 2,345,142 MullerMay 11, 1943 2,635,055 Figdor Apr. 14, 1953 2,637,665 Dodge May 5, 1953OTHER REFERENCES Printing Inks, Carleton Ellis, Reinhold PublishingCorp. (1940),pp. 100, 101, 205, 206.

Healey: Paint Manufacture, March 1943, XIII, pp.

Rudd: I. Oil Color Chem. Assoc., v. 21 (1944), pp.

1. METHOD OF PRINTING IN PAPER, PAPER-BOARD AND THE LIKE WITH PRINTINGINK CONTAINING AT LEAST A PIGMENT AND AN OLEAGINOUS VEHICLE, WHICHCOMPRISES APPLYING SAD PRINTING INK TO A PAPER, PAPER-BOARD AND THE LIKEPROVIDED ON THE SURFACE TO BE PRINTED WITH A THIN AND CONTINUOUS COATCONSISTING ESSENTIALLY OF A WATER-INSOLUBLE HIGHER FATTY ACID SALT OF AMETAL HAVING A VALENCY OF AT LEAST TWO, SAID CONTINUOUS COAT BEINGPRESENT UPON SAID PAPER PRIOR TO THE APPLICATION OF SAID PRINTING INKTHERETO AND SAID COAT AND SAID PRINTING INK BEING DIFFERENT FROM EACHOTHER SAID WHOLLY INDEPENDANT OF EACH OTHER PRIOR TO SAID APPLICATION,AND SAID OLEAGINOUS VECHICLE HAVIN A SOLVENT ACTION UPON SAID SALT INSAID COAT AND SAID SALT IN SAID CAOT HAVING A DRYING ACTION UPON SAIDINK, WHEREBY MUTUAL INTERACTION BETWEEN SAID COAT AND SAID INK OCCURS.